Spring boot如果findById返回null或找不到，如何返回Json？

@GetMapping("/api/{id}")
public ResponseEntity<?> getById(@PathVariable("id") Long id) {
    // 调用findById方法获取数据
    Optional<Data> data = dataRepository.findById(id);

    if (data.isPresent()) {
        return ResponseEntity.ok(data.get());
    } else {
        return ResponseEntity.notFound().build();
    }
}

@ControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(NotFoundException.class)
    public ResponseEntity<?> handleNotFoundException(NotFoundException ex) {
        // 返回自定义的错误消息或者一个空的Json对象
        return ResponseEntity.notFound().build();
    }
}

public class ApiResponse<T> {
    private boolean success;
    private T data;
    private String message;

    // 省略构造方法、getter和setter
}

@GetMapping("/api/{id}")
public ApiResponse<Data> getById(@PathVariable("id") Long id) {
    // 调用findById方法获取数据
    Optional<Data> data = dataRepository.findById(id);

    if (data.isPresent()) {
        return new ApiResponse<>(true, data.get(), null);
    } else {
        return new ApiResponse<>(true, null, "Data not found");
    }
}